中位牵引前移犬面中份骨骼的实验研究

目的 为弥补传统治疗面中份发育不全方法不足,本研究采用以上颌骨承力,中位牵引上颌向前,观察其可行性。方法 16周龄杂种犬14只,随机分为对照组8只,实验组6只。所有犬在上颌各骨缝的前后种植钛钉,作为骨标志。实验组犬安置特制牵引支架和牵引钩,橡皮圈连接,向前持续牵引,牵引力值约为600g,牵引前后进行临床和X检查及头影测量。1个月后处死,做组织学观察。结果 实验犬上颌逐渐前突,咬合关系呈现Ⅱ类错(牙合)。骨缝前后骨标志点间距离测量结果提示,前颌骨前移最明显,上颌骨次之,颧骨前移不多。对照组与实验组颅底角度变化差异不显著,未见上颌逆向旋转。实验犬各骨缝大量新骨生成,大量的成骨细胞,成纤维细胞沿张力方向排列,前颌缝尤为明显。结论 本牵引装置可有效地前移上颌,作用力更直接,避免了上颌的逆向旋转。

Protraction of midfacial skeleton at its medium position : Experimental studies in dogs

Objective In order to obviate the problems of traditional technique, a new midfacial skeleton protraction was developed. The midfacial skeleton was protracted by bone-borne forces other than by teeth-borne forces, which applied at a medium position, near the resistance center of midfacial skeleton. Through experiment, the possibility of midface protraction at the medium position was explored. Methods A protraction system was developed, it consists of three parts: a rigid external framwork, a bone hook, and elastic. Fourteen 16 week mongrel dogs were randomly assigned into two groups: the control (n=8) and the experimental groups (n=6). Four pairs of titanium bone markers were fixed on either side of suture of all animals. The control group was normally fed. The experimental group was fitted with a distraction device and a forward elastic force was exerted for 1 month. Clinical observation and X-ray examination were performed at the beginning and end of distraction period. All animals were killed at the end of the force application period. Histological study was made on the new bone specimen. Results All experimental animals appearances a progressively increasing anterior movement of maxilla and the occlusal relationship were in an Angle Class Ⅱ until the end of the experiment. The increasing distance between every pair of bone markers showed that premaxilla advancement was more than that of the maxilla. Next was the zygoma. There was no obviously change in the basilar-maxillary angle and counterclockwise rotation between the control and the experimental group animals. There was active osteogenesis in sutures of experimental animals, especially in premaxillar-maxillary sutures. The number of osteoblasts and fibroblasts increased dramatically and new bone formations was found at the edge of the suture. The osteoblasts and fibroblasts apposited along the direction of the force. Conclusion This technique can provide significant advancement of maxilla. The force was direct, which can avoid the counterclockwise rotation of maxilla.